Non-Pollinating Afrotropical Fig Wasps Affect the Fig-Pollinator Mutualism in Ficus within the Subgenus Sycomorus

Abstract

Ficus are species-specifically pollinated by chalcidoid wasps (Agaonidae), and the fig tree-fig pollinator mutualism has long been studied. A diversity of other chalcids, both gall-makers or parasitoids, co-occur in each monoecious Ficus species, and use the fig resource by developing in ovaries that they transform into galls. The oviposition sequence and impact on the mutualism of these non-pollinating fig wasps were studied on two Ficus species of the subgenus Sycomorus in the Ivory Coast. Field observations, fig measurements and counts of wasps and seeds from mature figs were conducted. Four groups of fig wasp species oviposit in the ovaries at different stages of syconial development, and were demonstrated to lay eggs in the internal ovary layers; the most external flowers seem to be protected against oviposition and thus develop into seeds. Non-pollinating wasp species, by parasitizing pollinator larvae or by competing for oviposition sites, have a significant negative impact on the pollinator population and dynamics, and thereby on Ficus male function (i.e. pollen dispersal). In contrast, but for one species, they do not affect the seed production, that is, the tree female function.